Obamas pay tribute to Nancy Reagan as 'proud example'

US President Barack Obama and his wife Michelle praised former first lady Nancy Reagan, who died Sunday at age 94, as a "proud example."
The Obamas said Reagan transformed the role of first lady during her 1981-1989 White House tenure, and later became an advocate for millions suffering from Alzheimer's disease like her husband, president Ronald Reagan, who died in 2004.